Design Patterns
Станкевич Ф.В.
Design Patterns
Creational Design Patterns
•
Singleton
•
Factory & Factory method
•
Abstract Factory
•
Builder
•
Prototype
Structural Design Patterns
•
Decorator
•
Adapter
•
Façade
•
Bridge
•
Proxy
•
Composite
Behavioral Design Patterns
•
Iterator
•
Strategy
•
State
•
Observer
•
Command
•
Memento
•
Chain of Responsibility
•
Mediator
2
Creational Design Patterns
3
Factory
4
Design principle:
Program to an interface,
not an implementation.
But every time you use new,
that’s exactly what you are
doing.
5
What’s wrong with “new”?
1. The code is not closed to
modification!
2. The code is changed as
new as new classes are
added
6
Factory Method Example
The code is still
parameterized
7
Factory Method UML
class Factory Pattern
Creator
Product
+
+
FactoryMethod()
AnOperation()
ConcreteCreator
ConcreteProduct
«instantiate»
+
FactoryMethod()
return new
ConcreteProduct
8
Builder Pattern UML
The Builder Pattern separates the construction of a
complex object from its representation so that the
same construction process can create different
representations
class Builder Pattern
Director
+
Construct()
for all objects in
structure {
builder->BuildPart()
}
Builder
-builder
+
BuildPart()
ConcreteBuilder
+
+
Product
BuildPart()
GetResult() : void
9
Example: Vacation Builder
class Builder Pattern
AbstractBuilder
Client
+
main(String[]) : void
+
+
+
+
+
+
buildDay(String) : void
addHotel(String) : void
addReservation(String) : void
addSpecialEvent(String) : void
addTickets(String) : void
getVacationPlanner() : void
VactionBuilder
+
+
+
+
+
+
addHotel(String) : void
addReservation(String) : void
addSpecialEvent(String) : void
addTickets(String) : void
getVacationPlanner() : void
buildDay(String) : void
10
Singleton Pattern
class Singleton
Singleton
-
uniqueInstance
singletonData
+
Instance()
return uniqueInstance
SingletonOperation()
GetSingletonData()
+
+
11
Behavioral Design Patterns
12
Strategy UML
13
Strategy Example
14
Strategy
15
State
Allows an object to alter its behavior when its internal state changes.
16
State UML
17
State
18
Template method UML
19
Example: Template Method
20
Structural Design Patterns
21
Adapter Pattern
22
Problem to solve
Your
Existing
System
Vendor
Class
The interfaces doesn’t match
23
Adapter
Your
Existing
System
Vendor
Class
Adapter
24
Adapter
Your
Existing
System
No changes
Vendor
Class
Adapter
No changes
New code
25
Adapter UML
26
Adapter Example
Use adapter
Proxy
Client
Proxy
Real Subject
29
Proxy UML
30
Proxy
31
Façade
32
Façade UML
33
Façade Example
Литература
• С.Стелтинг, О.Маассен - Применение шаблонов JAVA
• М.Гранд - Шаблоны проектирования в Java
• Э.Фримен, Э.Фримен – Паттерны проектирования
35
Observer
36
Command
37
Abstract Factory UML
class Families of ingredients
AbstractFactory
Client
+
+
CreateProductA()
CreateProductB()
AbstractProductA
ProductA2
ConcreteFactory1
ProductA1
ConcreteFactory2
AbstractProductB
+
+
CreateProductA()
CreateProductB()
+
+
CreateProductA()
CreateProductB()
ProductB2
ProductB1
38
Design Patterns
Станкевич Ф.В.